Items_into_Rooms.cpp

// A courier company has to deliver N items with different heights.
// All the items have to deliver to one building only.

// The building has K rooms inside indexed 0,1,..-K-1, and the heights of the rooms 
// are different. All the rooms connected with each other and has only one entry point, 
// e.g, you can reach room-1 from room-0 only, room-2 from room-1 only, ..so on.

// Now the task of the delivery agent is to keep the items inside the building.

// To keep the items into the rooms, delivery agent has to follow these rules:
//  - Agent can't keep, two goods in same room.
//  - As there is only one entry point, If the height of some room is less than 
//    the height of an item, then the item will be stopped before that room, 
//    so are the items behind it.
//  - Agent can rearrange the order of items to keep them inside the building.
   
// Return the maximum number of items, the delivery agent can keep inside the building.

// Input Format:
// -------------
// Line-1 -> two integers N and K, number of items and number of rooms.
// Line-2 -> N space separated integers, heights of the items.
// Line-3 -> K space separated integers, heights of the rooms.

// Output Format:
// --------------
// Print an integer as result.


// Sample Input-1:
// ---------------
// 4 5
// 4 3 4 1
// 5 3 3 4 1

// Sample Output-1:
// ----------------
// 3

// Explanation:
// ------------
// We can first keep the item of height 1 in room 4. 
// Then we can keep the item of height 3 in either of the 3 rooms 1, 2, or 3.
// Lastly, we can keep one box of height 4 in room 0.
// There is no way we can keep all 4 items in the building.


// Sample Input-1:
// ---------------
// 5 4
// 1 2 2 3 4
// 3 4 1 2

// Sample Output-1:
// ----------------
// 3

// Explanation:
// ------------
// Notice that it's not possible to keep the item of height 4 into the building,
// since it cannot pass the first room of height 3.
// Also, for the last two rooms, 2 and 3, only items of height 1 can kept.
// In room 2 or 3, keep item of height 1.
// In room 1, keep item of height 2.
// Finally in room 0, keep item of height 3. 
// We can keep 3 items maximum.



#include<bits/stdc++.h>
using namespace std;
int main(){
    int ni,nr;
    cin>>ni>>nr;
    vector<int> items(ni,0);
    vector<int> rooms(nr,0);
    for(int i=0;i<ni;i++){
        cin>>items[i];
    }
    for(int i=0;i<nr;i++){
        cin>>rooms[i];
    }
    sort(items.begin(),items.end());
    int x=items.size()-1;
    int res=0;
    for(int i=0;i<rooms.size();i++){
        if(x<0){
            cout<<res;
            exit(0);
        }
        if(rooms[i]>=items[x]){
            x--;
            res++;
        }
        else{
            x--;
            i--;
        }
    }
    cout<<res;
}